If you look at the actually geometry of a built frame, I don't think you'll find this assertion to be true (just checked a 79 Colnago, a 73 Bertin, an 84 Mercian, a 59 Soens, and a 76 Stout before I got sufficiently convinced). Brazed up, a road frame's dropout axle slots are not horizontal at all, but rather they are almost exactly perpendicular to the seat stays (when viewed from the side of the bike, of course).
So, that means that mounting the brake behind the bridge puts the brake pads the same number of degrees off of perpendicular as mounting ahead of the bridge, it's simply two different directions.
I, too, have left well enough alone on this particular topic...all my bikes have the brake behind the bridge. None of my bikes have racks of any sort.
Cheers,
Scott
Scott Minneman San Francisco, CA USA
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Harvey Sachs Sent: Tuesday, January 18, 2011 6:34 PM To: Classic Rendezvous Subject: [CR] Rear Brakes Attached Forward of the Bridge
Consider a bike with horizontal drop-outs. In such a case, the brake mounted conventionally (rearward of the seat stays) is likely to tolerate more back-and-forth adjustment of the rear wheel w/o needing brake pad adjustment than one with the brake mounted forward. Of course, with vertical drop-outs, it doesn't matter.
The only time I was tempted to mount forward of the stays was, as I recall, late one night with a caliper too long for the conventional position. Otherwise, I've left well enough alone.
your mileage may vary.
harvey sachs
mcLean va